code: def __init__(self):
      self._trial_iterations = collections.defaultdict(list)
  
imports: import collections
  import json
  import os
  from pathlib import Path
  import random
  import time
  from typing import Dict, List, Optional
  import ray
  from ray import train, tune
  from ray.train.data_parallel_trainer import DataParallelTrainer
  from ray.tune.experiment import Trial
  from ray.train.tests.util import create_dict_checkpoint, load_dict_checkpoint
label_desc: Use image node_id 1 to create a new StatefulCallback object from inherited base classes: tune with example: obj = StatefulCallback()